1. A.W. Conway and J.L. Synge (Eds.) The collected papers of W.R. Hamilton, Geometrical Optics, Cambridge University Press, 1931.
2. The Scientific Papers of J.C. Maxwell (Ed. W.D. Niven) Dover Publications, N.Y., 1965.
3. R.K. Luneburg The Mathematical Theory of Optics University of California Press 1964., 86
4. A. Sommerfeld Lectures on Theoretical Physics Vol. IV Optics Academic Press 1964. 355.
5. O.N. Stavroudis, The optics of rays wavefronts and caustics, Academic Press, 1972, 14.